Reptile & Amphibian Forums

Mostly because they can't, maybe for a number of reasons. These seem to be related to seasonality in one way or another, either as it affects the mother, or the likelihood of survival of the eggs or young.

There are very few places where monitors live which are not seasonal, whether in terms of temperatures or rainfall, or both combined. Even where we would regard seasonal variation as slight, most of the resident animals nonetheless have distinctly cyclic breeding patterns that are cued to varying resources.

As an example, take monitors in tropical northern Australia, where the summer months (November-April) are very hot and very wet, and midwinter (June-August) is relatively cool and very dry. All 12 monitor species there except one mate between early May and mid-June, and lay one clutch 3-4 weeks later. The exception is V. glebopalma, which appears to mate in November.

Most of these monitors are relatively inactive from July to October, when food is scarce owing to cool weather, very dry conditions, and desolation at ground level caused by dry season fires. Monitor food starts to reappear with the first rains (Oct-Nov), and there seems to be plenty to eat all the way through to June, whether we are talking about insects, other herps, bird eggs and so forth, or whatever. Most monitors (except V. glebopalma) are in poor condition by the time the rains begin, but they very quickly put on weight, and it is rare to see a scrawny animal more than a couple of weeks past the start of the wet season. However, all but glebopalma go for another 5-7 months before there is any courtship or mating observed. If you handle animals anytime during the wet season they are in good condition, and roadkilled ones tend to have large fat bodies from quite soon after the rains begin. If "condition" was the only factor, they could probably breed much earlier in the wet, and there would be time for most females to produce 2, 3 or maybe 4 clutches. However, they don't. Whatever you want to believe, there is just no evidence at all that females of these species lay more than a single clutch per year.

In fact, I'd have been happy to find such evidence. I don't care what the literature says, if the animals do it anyway, I want to know that. Why anyone would think I (or anyone else) would do all this fieldwork just to back up some preconception is hard to understand.

This is not dismissable by a "you didn't see it" argument. The pattern is based on dozens of radiotracked animals that were observed daily (by me, and by others), and is exactly what you see from checking the reproductive condition of roadkilled animals as found all year round. For the species I've studied, males rather abruptly change their activity patterns and begin to seek out females (which they have ignored or avoided up to then, again as based on knowing where all animals were and what they were doing every day for months). Most males of V. glauerti, glebopalma, scalaris and tristis find and mate with 3-5 females whose home ranges overlap or adjoin their own, and most females mate with at least 3 males over about 4-5 days of intense interactions -- any one female cycles once, but different females in an area may start to cycle any time in a 2-3 week window. 3-4 weeks after mating, each of these females goes and digs a nest and lays, the process usually taking 1.5-2 days. I see them the day before and the day after, and the day in between you have an arboreal species down in a root hole under a stump, where males never go and females go only once a year – you bet they laid, and they show it.

If females don't lay when it seems that they could, in terms of energy reserves, why might that be? The most reasonable answers may be that monitor eggs don't cope well with flooding or saturated substrates, and/or that hatchling monitors can't survive if they emerge during the dry season. Laying in June-July keeps nesting sites no wetter than they were when the female chose them, and places hatching in the early wet season, with several months to feed and grow before the environment shuts down the cafeteria.

Why glebopalma is shifted about 6 months is a fair question. They appear to nest far back in rock outcrops where the soil is nothing but sand, and is probably fast-draining. Hatchling glebos appear in May-June when things are drying out, just before fire season. Interestingly, the only areas that don't burn are these outcrops, and for a month or two after everything else is ashes there are still lots of lizards, grasshoppers and so on in areas protected from fire by their rocky perimeters. Adult glebos do not lose much condition during the dry season compared to other monitor species, perhaps because their rocky habitats remain unburned and in fact get rather crowded with prey animals that have fled fires in the surrounding areas.

What real, wild monitors show us is that nature places constraints on reproduction, and that they don't multiclutch, possibly because it would be pointless to do so (eggs that do not hatch or young that fail to survive are a big waste of energy). I've concentrated on a single geographic region, but you could make similar arguments based on egg and hatchling survival for warm-temperate areas, and for both temperate and tropical deserts. It is less clear that this reasoning applies to the really-wet tropics where there isn't a pronounced dry season, and areas like this (mostly in western Indonesia) are about the only places where monitors have been reported to lay more than one clutch a year. The evidence for that is still indirect, based on examining water monitor carcasses at skinning factories – some females had recently laid, and had a second clutch coming along that the investigators felt could have been yolked up and laid within a month or two.

This does relate directly to multiclutching in captive monitors, but I'll let you try to figure out how, for a while.

From the critters you are describing I would guess it has to do with their habitat. You said very dry and very wet. These make for unstable habitats. I have never claimed they multiclutched in the wild, but it is possible to do. I believe the reason they don't seem to in the wild is because they have more things to worry about, like personal survival. What about the critters that live in a more stable habitat. One with plenty of food and water and less predators? Has anyone done a study on these critters to see if they multiclutched?

Scott
-----
Do not meddle in the affairs of dragons, for you are crunchy and taste good with ketchup.

One way to look at this as Kap says is microhabitat and nesting stability for incubation...find continual food sources, a relatively stable (micro-)habitat within the seasons and you might have good information leading towards multi-clutching ability in the wild = we know most varanids can multi-clutch, but what limits them from doing this in wild could be opposite to what is offered to them in captivity: constant/regular food sources, adequate nesting sites, 24/7 photo periods, over-production of hormones, sufficient calcium/phosphate levels to start - if the animals cannot reproduce what captive animals do, they will be able to multi-clutch in the wild populations. And then there is the evidence for 'sperm retention' which has been documented, and may have a good deal to do with this.

In the last few years staggering amounts of Varanus skins have been imported from chiefly from Africa (V. niloticus) and from Singapore (V. salvator). Export numbers of 100,000 and 750,000 annually - so what do these numbers have to do with multiclutching? Where do you find 100,000 animals of a sufficient size (3-5 feet 90% of the hide-skin sizes exported)? Where do you find 750,000 V. salvators in one local/province without wiping out an entire gene pool population? Well, multi-clutching would explain the high numbers of Varanus skins exported, and that although local populations have detrimental effects to these losses, the overall populations do not appear to suffer greatly (yet). Habitat loss is the great detriment to Varanus everywhere, and the rampant over-population of Homonids is the perhaps the key to this: reduced primary habitat produces high denisity populations of Varanus, whereby higher incidence of ritualized combat, territoriality and mortality rates increase among the male animals; the females are more sedentary, and do not forage to the extent males do, and may not be hampered as much effect as the more out-going males do? But the skin trade skin reports 'might' suggest that multi-clutching does occur in wild populations, and we just do not see the evidence for it yet....

There is good breeding reports (unpublished, but I have copies of these accounts) data for V. exanthematicus, V. niloticus and V. albigularis multiclutching, and in addition to their large clutch sizes would also support their skin-trade carrying capacities for both the wild and skin-trade populations.

Cheers,
mbayless

Sounds like you are describing someplace like the N coast of Irian Jaya, which is about as aseasonal as it gets on this planet. The monitors there are V. doreanus, indicus, jobiensis, prasinus and salvadorii, none of them reported to lay multiple clutches in the wild.

That point aside, you'd actually expect multiclutching in an environment that was far less than the monitor paradise you're describing. If there isn't any mortality (from predation, food shortages, bad conditions, etc.), animals don't die, and there is no reason to breed like flies. It's energetically expensive to lay eggs, and the basic lifetime goal of any female is to produce two young that survive to replace her (and a male). Things that live fast and die young have to produce tons of offspring to offset very high mortality rates (like flies), whereas species that have it easy, so to speak, mature late and have small numbers of young. It is actually not-so-good to behave like rabbits did in Australia, where, released from their usual set of checks and balances, they became their own worst enemies! At some point competition among individuals becomes a factor, and it works against you to keep cranking out the spawn.

The monitor species that produce large clutches (Niles, salvators, V. spenceri) don't share any set of habitat features; rather, they live in places where very, very few young monitors make it to reproductive age, probably owing mostly to high predation.

Someone will point out, I'm sure, that monitors in boxes come the closest to having no predators, no worries about food or water, and no seasonal variation (and not even any nighttime in some cases). At least some species respond by multiclutching (for reasons we don't need to debate again here), but if you think about that as a set of "causes", it would predict that they shouldn't breed at all, if they perceive themselves to be in paradise. Now, if they are really-really stressed and expect to die soon, that's the situation in which it would be logical to start multiclutching like crazy, in a desperate effort to produce any young that survive at all in a horrible environment.

Hmmm, somehow that didn't quite wind up in the way it started, being about monitor paradise and all. Nice try, though.

"Now, if they are really-really stressed and expect to die soon, that's the situation in which it would be logical to start multiclutching like crazy, in a desperate effort to produce any young that survive at all in a horrible environment."

This sounds strange. It is my experience that reptiles in captivity having intolerably high levels of stress do anything but get sick and die... I have never seen or heard of prolific reproduction resulting from animals stressed to the max in their captive environment. Are there other situations in captivity, aside from monitors, where you believe/have seen this to be the case?

Thanks,

Ian

That is not why they don't multiclutch, That is your opinion why you think they don't. That is fact.

The fact that you have no experience with multiclutching, disallows you from knowing anything about this. Its your opinion. and your opinion is from lack of knowledge. In any area of multiclutching.

Its clear, you have never had this happen. Its also clear, you have never seen it in nature. That means you have NO facts to make a definitive statement. You are guessing.

Its clear, you have read no definitive paper on this happening either, again you can only form opinion.

You and others, have not tested it, You or others have not attempted to study it in the field. So you make an exact statement, from lack of knowledge on a subject that has not been studied. ( science has names for people who do this)

I wonder how you predict what you haven't seen or studied? This is the type of statements that convince me your not a scientist, or a good biologist. Or why I have to hold your papers suspect. You know, you cannot make a statement like you have, don't you.

You are allowed opinion and it may be your opinion. But then we all have opinions.

It is fact, that monitors commonly multiclutch, from KD's at the national zoo, to hundreds of private collections. From Dallas zoo, which shows little captive breeding success(gouldi) to many records from zoos around the world, check the books. Many are cited in Daniel Bennetts books.

So, for you to make a statement like you do, the subject must be studied and tested and not by only you. Sir, that is science. thank you for your opinion. FR

I personally witnessed very high levels of monitor activity in Oct-Nov specifically in the Mt Isa area and throughout the top end and this was well before the rains had hit.

The rains then hit in Dec. and continued into April.

This would appear to be plenty of time for monitors to multiclutch.

The food supply was so abundant once the rains hit that a supply of nourishment for the multi clutching females would not be a problem.

Let me relate a story about this subject with another biologist, Daniel Bennett.

Of course he started with the same attitude that Our MS has, But he contained one other trait, he was willing to listen.

Of course, he is very bull headed, which means, his head was full of the same understandings that literature protrays.

It was his understanding, that reptiles, convert stored fat to yolk over the entire winter. That would make a complete reproductive cycle, a very long process. With that understanding, it would be easy to imagine that multiclutching would be difficult in a single season.

Well, he did come over and mingle with the devil. That is, to see for himself what this was all about, or better yet, where was I getting these ideas from. So, he looked for himself.

Well, I showed him all types of monitors doing all types of things. But one particular event, rocked his world. I showed him the belly of a V.kingorum, I did this, because with several of the small species, you can see the stored fat(like with some geckos). On the first day, I showed this internal fat in one female, then the next day, this fat was shrinking and ovum were enlarging, by the third day, there was no fat visible, only enlarged ovum. He comment was, I had no understanding, monitors had type of metabolic ability. It was a learning process.

He also could see, I was not doing anything out of normal. Only offering heat ranges that normally occured in nature. And of course food, but he also saw, it wasn't about lots of food.

It was about the ability to maintain the proper metabolism for short periods of time. It only took five or six medium feeding to create fat that creates enlarged ovum. Please understand, we in captivity, normally do not allow gorging like monitors do in nature. It may only take one gorging, to produce eggs. But thats only my opinion, from real experience.

The point being, the recorded times for a reproductive cycle, were from captivity and possibly from non-optimal conditions. For instance, we have had several species produce eggs, every two weeks.

The question is, are our conditions better then natures? some say yes, some say no. My opinion from experience with both is, its not even close, Nature is far superior, or nature really sucks and does not allow anything to live. Nature has a wide range of conditions, from worse to far better.

And lastly, if you read the lenght of time most books give as the reproductive period, there is indeed plenty of time. Thanks FR frogs eat bugs

I have never seen the number of bugs that I saw between Jan and April in the northern part of Aus. during the rainy season. I was particularly surprised at how active the lizards were in Nov. when it was extremely dry and had not rained much in the last 6 months. If there was food enough to be this active during the hot/dry period, there must have been way too much food once the rains hit. I remember having to clean the windshield every 30 minutes because there were so many bugs.

Four months of hyper food supply would appear to be plenty of time for many of the monitors to gorge and multi clutch year after year, as long as the rains kept providing the bugs.

Sorry, Frank, that's what happens with real monitors out bush. I'm reporting what they do. I've been there, and done a heap more field work than you have, and I know what the animals I studied did every day. Each female laid one clutch, period, end of story. I'm not sorry if this rattles your box, you can imagine anything you want about what happens with wild monitors, but until you have some evidence all you can do is rant.

I agree with some of Mark's post above, that those monitor species which have the most miserable prospects for survival of their young are the ones that natural selection would drive towards multiple-clutching, and that savs and albigs are on that list along with Niles, waters and spenceri. However, there are three ways that animals can respond to this: they can breed younger, they can lay a larger number of smaller eggs/clutch, or they can lay multiple clutches. We see the large clutches in the species I mentioned. Some others, such as tristis and gouldii, lay more eggs that are smaller than expected. And quite a few mature early: Vivien de Buffrenil has documented that where Niles are under very heavy harvesting pressures for the skin trade, more and more small females are breeding early. This may be happening in some populations of salvator as well. However, with the exceptions I've noted, there is next to no documentation that monitors lay multiple clutches.

It is odd, in fact, that these animals do not use every means at their disposal to compensate for high mortality. That was exactly the point of my post -- in energetic terms, yes, they could do it, but there is something out there that prevents it from happening. I provided some suggestions as to what that might be. I don't see you doing anything but engaging in personal attacks. Can you document multiple clutches in wild monitors? Please do, we're all ears.

Sir, I have no problem with that, but that only makes it your opinion. Not science or fact. In your experience, with the species your familiar with, with the limited experience you have, you have Not seen it. That would be fine. But does not limit their ability to multiclutch.

As a scientist, you "should" understand, That any species reproductive abilities is based on numerous conditions, these conditions not only vary, year to year, but even over much longer periods like centuries. To a species, decades or more, are a moment in time.

V.t.o and V.t.t. are a species that has successfully laid eggs every two weeks, much less once a month. So, indeed they have the genetic capability to do that. Now, it becomes under what conditions would or could this happen in nature. Maybe not under the current conditions on your site or with the age group your studying.

If you had extensive experience with captive monitors, you would understand, multiclutching is a job for the young, yes, its far more common with young monitors.

So you say that heavily impacted monitors can multiclutch, and you see more and more young gravid individuals. Yes, I can see that happening. If fact, that has happened on our study site, most likely a result of extented drough. We now see gravid females that are very very small and young, possibly as young as 9 months old.

This has also been seen in heavily collected areas with snakes. Like Mountain kings, in areas where they are heavily collected, you find more small adults, then before they were heavily collected. Please, remember, this too is hearsay, it has not been studied as far as I know.

So, your saying with V.tristis, there is no possibility of anything impacting the population? You know, like fires or floods, that would radically change exsisting populations. Your saying, that these events if occurred, would not effect the breeding stradegy of the adults you studied, how would you know this?

If I was to go by captive results, I would consider that recruitment is a task of the young, and full sized adults are not young. I would think that picking full sized adults would tend to lead you to believe that one clutch is normal. Yes, I would think that. I have to wonder, why don't you include the entire population? for instance, where where the young females and what did they do? Remember, in captivity, its mainly the young that multiclutch. In captivity, older individual females, are considered, non-breeders. Its not that they do not produce, its that they are not consistant. They normally do not even produce every year.

You also may consider that its not entirely the age of the female concerned, but the actual support, Its takes far more energy for larger females to produce, then it does younger smaller females that may weight 1/4 the weight of a larger female.

maybe just maybe, V.tristis, commonly multiclutch on your own study site, only the very small ones that you consider too small to breed. The reason I say this is, thats exactly what happened to us, on our study site. The funny part is, I knew small females could breed, we just did not see it until something natural caused it, drought. Not recruitment in good years after drought, but instead during the droughts themselves.

Again, you are trying to paint with a broad brush, when you only have a tiny brush. I suggest, looking at the entire population, I suggest looking at them over many different conditions, like cyclones, floods, fires and mans intrusions. I also understand, with current methods of study, there is to much intrusion on the animals, and can cause a level of stress, this level may me enough to effectively stop multiclutching. I do think it would serverly hinder captive females. Maybe a good test would be for you and a control, to test this on captive V.tristis.

Also consider, I do except your opinions based on your limited tests. But surely they do not make any of this impossible, or even unlikely. It only means, its unlikely in your experience and useing the tests you use. Remember, science suggests, if you bottle neck using an approach, then try another, particularly when there is some evidence that another approach is necessary. Thanks FR

Frank, you are giving the scientists that inhabit this forum, way to many bits of free advice that they can use in their future studies and then claim credit for the discoveries all on their own.

I'm sure any scientists that are worth their salt are taking notes on what to look for on their next trek into the wild.

I would think that it would be really easy to miss multi clutching in a field study, especially if you never thought to look for it.

The idea to focus your search for "multi clutching females" on young females is brilliant. Nobody could come up with that kind of idea without witnessing it themselves.

KL says "I would think that it would be really easy to miss multi clutching in a field study, especially if you never thought to look for it."

KL, it'd be about as easy to miss as it would be to overlook the loss of two wheels on your car. And I'm still waiting for the first "secret" from Frank that is either (a) a new idea not already in the literature, or (b) imaginary.

you sound like a kid who was sent to his room without desert.

Have you ever thought I could not care what you think and what you do. I don't.

The reality is, I have indeed helped many people have success with their monitors, even if its in some tiny way. And please consider, thats great for me. The truth is, I only want to help or care to help those who want to learn. Those that do not, I would love to send to you.

Please consider, I never claimed to invent anything, I merely presented conditions that allowed monitors to grow and reproduce in a normal timely manner. Whether others did some or all of it, is not my concern, I am only concerned with what I did and do. Is that so odd? Your the one who seems to be worried about firsts and whos and other bullbeans. I am merely having fun. Thanks FR

" Frank that is either (a) a new idea not already in the literature, or (b) imaginary. "

That's just wrong .... I have tons of old papers published by "scientist " before FR and other breeders started releasing husbandry and breeding information . Most of them you can find very little usefull information on feeding , temperatures , much less breeding them . Infact if you fed and cared for your monitors (or other reptiles for that matter ) your monitors the way most of the old papers say to you won't have to worry about every providing a nest site to your lizards since they will be long dead before they even come close to needing one.

Give credit where credit is due even though you don't always agree with it . Captive breeding has brought science a wealth of information and not just in the herp field .

Science has also brought a wealth of information to captive husbandry (you just have to know where to look for it as it is not usually published directly related to reptiles )

Stella
-----
Stella St.Pierre
www.bluetegu.com - Ron St.Pierre

I don't disagree with you entirely, Stella, but it's also incorrect to say that the older scientific literature does not contain information relevant to current husbandry practices. For example, Ray Cowles (1930)published a long paper on the ecology of Nile monitors where he argued, among other things, that monitors needed to be able to dig burrows in order to regulate both humidity and temperature. The European keepers paid attention to that, the Americans generally didn't. If you look at other papers, such as Stebbins and Barwick (1968) on the thermal ecology of free-ranging lace monitors, or any of several physiological papers by Al Bennett (early 1970s), it is very clear that monitors have very high needs for both temperatures and food, and are quite unlike other reptiles in both respects. Bennett said this was a consequence of monitors using aerobic metabolic pathways (much like mammals do), rather than behaving like other reptiles in using anaerobic metabolism for activity. There are also a number of 'ecology' papers by Eric Pianka and others starting in the early 1970s that emphasize the high thermal and food reqirements of monitors.

What I think you are saying is that this stuff did not get into the herpetocultural literature in English, and that's largely true. However, that's not to be laid to your 'scientists', but rather reflects on the conservatism of the herpetocultural community when it comes to applying scientists' results. Again, the Europeans paid a lot more attention a lot earlier to these findings, and were successful in both keeping and breeding monitors at a time when the yanks still treated them as if they were ordinary stupid reptiles.

Just because I don't always agree with science does not mean I blame it or hate it .
Dissension is a long ingrained part of being an yank our country was based on it .
Don't take it personally ... hell I don't always agree with FR either .

I did not say that all old papers were worthless ... I said that there was very little usefull information in most of them that could be applied to captive husbandry .(keyword most )

Europeans not only had an advantage when it came to a language barriers but they also had better access to animals than most American did at that time .
And some of us "yanks" have been keeping reptiles in natural type enviroments for as long as we have been keeping them .

Ever think that some of us are just not as old as some of those Europeans who bred them first? maybe that's why they did it first (Ron is only 35 btw - women don't tell do don't ask how old I am )

Ron and I did not breed monitors because of what we read in a paper . If we had to rely on what we read in papers that long ago we would have never bred anything.

Long before we ever bred a monitor we had already bred many other species of snakes/lizards /frogs/fish .
We applied much of what we had learned from working with other reptiles to come up with what we did for our monitors .
And like Frank much of what we applied to our husbandry was from information we had gathered from obserbing other reptiles in the field .

South Florida is full of introduced exotics that have learned to adapt to conditions not natural to them and thrive and both Ron and I have spent many years observing them and taking notes.
We applied much of what we saw these exotics adapt to and use to our own husbandry and enviroments .
I think a scientist biggest disadvantage is the misconseption that change happens over a long course of time ... I don't think you guys realize how quickly things can change and adapt .

Just because you see one thing in the wild does not mean it will always remain true .. change the enviroment and you will see different behaviour ... they will either learn to adapt of they will fail .

The same can be said for life in a cage ... you can take the same four lizards and raise them seperately and they will behave differently than if you raised them together .... raised indoors these same lizards will usually behave different than raised outdoors ... raise these same four lizards together in a cage of a certain size and they will get along put them in a cage four or five times the size and they might not get along so well anymore because they don't no longer have to . Succesful keepers are those that learn to adapt ,apply and change when they have to so they don't fail not ones who rely on what is written because someone thought they had some proof when they saw something .
-----
Stella St.Pierre
www.bluetegu.com - Ron St.Pierre

"This has also been seen in heavily collected areas with snakes. Like Mountain kings, in areas where they are heavily collected, you find more small adults, then before they were heavily collected. Please, remember, this too is hearsay, it has not been studied as far as I know. "

This is also true with corn snakes in the Miami area .
I have collected corns there that were so tiny you would never think they were capable of laying eggs.
-----
Stella St.Pierre
www.bluetegu.com - Ron St.Pierre

How can you say that? Because you've never seen it personaly?
Well, I've never personaly been to Anartica, does that mean it aint really there?
You are starting to sound like the poeple that thought Columbus was crazy and was going to fall off the side of earth.
Maybe the world is flat where you live.

Scott
-----
Do not meddle in the affairs of dragons, for you are crunchy and taste good with ketchup.

NOUN: 1a. The use of words to express something different from and often opposite to their literal meaning. b. An expression or utterance marked by a deliberate contrast between apparent and intended meaning. c. A literary style employing such contrasts for humorous or rhetorical effect. 2a. Incongruity between what might be expected and what actually occurs.

Umm, you do realize that the title of my responding post refers to Frank's incredulity?? Just checking. Last I looked, the earth wasn't flat.